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The Centers for Disease Control and Prevention (CDC) has issued interim guidelines for health care providers in the evaluation, testing and management of infants with possible congenital Zika virus infection. The guidelines, developed in conjunction with the American Academy of Pediatrics, were published in the January 26 issue of the Morbidity and Mortality Weekly Report.

Zika virus is a mosquito-borne infectious disease primarily transmitted by Aedes mosquitoes. These mosquitoes, which also transmit dengue and chikungunya viruses, are found throughout much of the Americas, including parts of the United States. The Brazil Ministry of Health is currently investigating the possible association between Zika virus and a reported increase in the number of babies born with microcephaly. Microcephaly is a condition where a baby’s head is much smaller than expected, and may include a range of other problems depending upon the severity of the condition.

About 1 in 5 people infected with Zika virus become symptomatic. Characteristic clinical findings are acute onset of fever, rash, joint pain, and/or red eyes. Other commonly reported symptoms include myalgia and headache. Clinical illness is usually mild with symptoms lasting for several days to a week. Severe disease requiring hospitalization is uncommon and case fatality is low. However, there have been cases of Guillain-Barre syndrome reported in patients following suspected Zika virus infection.

The CDC advises that when an infant is born with microcephaly or intracranial calcifications to a mother who was potentially infected with Zika virus during pregnancy, the infant should be tested for Zika infection. In addition, further clinical evaluation and laboratory testing is recommended for the infant. The mother should also be tested for a Zika virus infection, if this testing has not already been performed during pregnancy. An ophthalmologic evaluation, including retinal examination, should occur during the first month of life, given reports of abnormal eye findings in infants with possible congenital Zika virus infection.

For infants with any positive or inconclusive test findings for Zika virus infection, health care providers should report the case to the state or local health department and assess the infant for possible long-term sequelae. This includes a repeat hearing screen at age 6 months, even if the initial hearing screening test was normal, because of the potential for delayed hearing loss as has been described with other infections such as cytomegalovirus.

For infants with microcephaly or intracranial calcifications who have negative results on all Zika virus tests performed, health care providers should evaluate for other possible etiologies and treat as indicated. Under the CDC guidelines, pediatric health care providers are advised to work closely with obstetric providers to identify infants whose mothers were potentially infected with Zika virus during pregnancy based on their travel history or residence in an area with Zika virus transmission and to review fetal ultrasounds and maternal testing for Zika virus infection.

No local transmission of Zika infections has occurred in California, according to the California Department of Public Health (CDPH). Zika infections in California have been documented only in persons who were infected while traveling outside the United States. While the risk for transmission of Zika, chikungunya or dengue viruses is still low in California, infected travelers coming back to California can transmit these viruses to Aedes mosquitoes that bite them. This may lead to additional people becoming infected if they are then bitten by those mosquitoes.

While there has been no occurrence of Zika transmission in California, CDPH will be holding a conference call for health care providers on Wednesday, February 10, from 9-10 a.m. The call will provide information and updates about the Zika virus, and give providers the opportunity to ask questions. To join the conference call dial (866) 216-6835 and key 839641 the participant passcode.